Method of protecting metal heated to a high temperature against oxidation



v lf' through l'lED STATES PATENT OFFICE.

HERMAN B. KIPPER, OF MUSKEGON, MICHIGAN.

mnrnon or Paorncrms METAL Snaren To A HIGH TEMPERATURE AGAIST OXIDATION.

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Application filed May 19,

To all "u1/tom 'it 72mg/ concern.'

Be it known that l, .HERMAN l. Krrrnn, a citizen of the United States of America, residing at Muskegon, in the county of Muskegon and State of Michigan, have invented certain new and useful Improvements in Methods of Protecting Metal Heated to a vHigh Temperature Against Oxidation, of which the following is a specification.

The present invention relates to a method of producing cyanids or nitrogenous compounds through the action of nitrogen gas on a mixture of sodium carbonate or other sodium salts, ,carbon and iron.

lt has been known for a number of years that if sodium carbonate, coke and iron are heated together to about 900 to 1000O C. and nitrogen or producer gas is passed through the heated mass, sodium cyanid and other sodium nitrogenous compounds are formed. the mass of compounds thus formed at the higher temperature, steam is passed at a temperature of about 400O C., ammonia is formed, possibly somewhat according to the following reaction This knowledge notwithstanding, the process has never been successfully commercially developed. The reason for this is that the process must be carried out in a closed metal vessel at a temperature of 900 to 1000o C. and that in heating a metal vessel to'such temperature by an ordinary fire the excess oxygen left in the gases will cause rapid oxidation and destruction of the metal.

'.l`he chiotl object of my invention is to obviate this drawback. that is to say, to heat the vessel so that while the desired temerature for the formation of nitrogenous con'ipounds can be retained for almost any length of time. oxidation and consequent destruction of the metal vessel will be prevented.

To accomplish this object my invention consists chiefly in that the metal reaction vessel is heated to about 1000O C. over a high column of coke or coal, theqcombustion' of which is directed in suclna` way that a heating gas is produced which consists of a mixl ture of nitrogen and carbon 'monoxid (CO) with but a minimum percentage of carbon dioxid. i

The metal reaction vessel contains the mixture of sodi um saltsuch as sodium carbonate iron and coke and through it is passed either3 Specification of Letters Patent.

1919. serial No. 298,118.

nitrogen or producer gas, that is, one composed of carbon monoxid and nitrogen, and at either atmospheric or superatmospheric pressure I find that at high pressures the nitrogen more readily combines with the sodium salts so that lower heating temperature may be used and consequent better protection of the reaction vessel is secured.

By admixture of potassium salts I have also found that the reaction temperature is lowered.

By burning a layer of coal, as for instance with ordinary steam boilers, the oxygen of the air passing through the coal bed burns the combustible portion of the latter mostly' to carbon dioxid. By using a higher bed of coal or coke the oxygen of the air in passing through it is almost fully consumed 'to form carbon dioxid. In the upper portion ofthe bed, however, the carbon dioxid in the presence of the hot coal or coke is decomposed or reduced to form carbon monoxid according to the following chemical equation The carbon monoxid thus produced can be conveniently used as a fuel gas.

In all ordinary processes of combustion, the oxygen of the air, of which there is about 20%, alone acts chemically while the 80% of the nitrogen gas contained in the air remainsl practically inactive chemically ,an-d acts therefore merely as a diluent.

In burning carbon (coke or coal) to carbon monoxid only part of the total heat of chemical reaction is evolved, thus:

C+OICO-l-about 2500 Cal CO-|-():CO2+about 5500 Cal It will thus be seen that all the energy of the combustion of the coal or coke is not utilized directly in heating thecylinder in which the cyanid compounds are formed. The carbon monoxid, or producer gas, may, however, be withdrawn and used for other purposes, such as drying, heating of the cyanid to 4000 C. before passing steam through it, and' might be employed for any other purpose in which gaseous fuel can be advantageously used.

It is known that at high temperature carbon dioxid is dissociated or decomposed into carbon monixid and oxygen. I therefore attempt to keep thb percentage of carbon dioxid formed during combustion as low as possible.

Patented Nov. 9, 1920.

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f While I do not wish to confine myself to any specific form of apparatus, I shail de scribe herein one form which has proved to be the simplest devisable and which can be recommended for carrying out the process on a large scale.

In the accompanying drawing the apparatus is more or less diagrammatically illustrated. l a denotes a producer similar to an ordinary gas producer and made of steel plate in a rectangular shape. This is lined first with insulating brick as at ZJ and thenwith lire brick as at c. In the upper portion of this apparatus one or more cylinders (l made of heavy Wrought iron pipe or any suitable metal or alloy are placed. These cylinders may be arranged in any suitable manner to be revolved.

Through the cylinder d a mixture of sodium salts, such a sodium carbonate, iron and coke and nitrogen or producer gas are passed. The producer is filled with a high column of coke or coal and at the bottom of the producer an air inlet e is provided through which an amount of air .is passed through the coal or coke bed which amount is in a suitable proportion to the column of carbon so as to form a heating gas consistl 80 ing chiefly of carbon monoxid with .a minimum amount of carbon dioxid. The ccmbination of the coke or coal Will, as stated before, furnish a heating gas consisting of carbon inonoxid' and only a very small per centuge or carbon dioxid, which gas .will 35 heat the vessel I] to the desired temperature without causing its oxidation. y

In order to prevent clinkering we have most advantageously used an ashless fuel such as petroleum coke. 40

Vi'hat I claim and desire to secure by Letters Patent is l. In the process of producing nitroge l nous compounds by heating a mixture of sodium salts with carbon and iron in a metal vessel to al high temperature and passing nitrogen or producer through said \'es sel, the step of protecting the metal vessel. from oxidation, consisting in heating said vessel by burning a carbonaceous fuel to carbon monoxid and a minimum of carbon dioxid, and preventing excess of oxygen.

2. The herein described method of protecting metal heated to high temperature from oxidation, consisting in heating said metal by burning acarbonaceous fuel to carbon monoxid and a minimum of carbon dioxid, and prevel-ting excess of oxygen. 'i

In testimony' whereof I aliix my signature in presence of two witnesses.

HERMAN B. KIPPER.

Witnesses:

ROBERT It. VnLIn, MAX D. ORDMANN. 

